1. Field of the Disclosure
The present disclosure relates to an information processing apparatus, an information processing method, and a storage medium for determining the number of gradation levels to be obtained after gradation conversion is performed for reducing the number of gradation levels of data to be processed corresponding to a predetermined number of gradation levels.
2. Description of the Related Art
A printing apparatus that performs printing of images may perform printing of an image based on image data which has been compressed in a lossy-compression method. A Joint Photographic Expert Group (JPEG) method is an example of such a lossy-compression method. Image data compressed in the JPEG method is expanded, and an image based on the expanded image data is printed on a recording medium by a printing apparatus.
As described above, the JPEG method is a lossy compression method. Therefore, image degradation called mosquito noise may occur in an expanded image. The mosquito noise arises from quantization processing in JPEG compression. In the JPEG method, by quantization processing for an image which has been converted into a frequency by discrete cosine transform (DCT), in particular, information of a high-frequency component is eliminated. Accordingly, when expansion processing is performed, for example, a signal value which does not originally exist around edges within the expanded image may be generated as the above-mentioned mosquito noise.
In Japanese Patent No. 4053460, processing for eliminating mosquito noise from image data obtained by expanding compressed image data, is suggested. Specifically, image data obtained by expanding compressed image data is divided in units of blocks, noise determination processing is performed, and the type of noise and the degree of occurrence of noise are determined. Then, switching parameters (a quantization threshold value, an error determination threshold value, and a diffusion factor) in half tone processing for creating printing data, based on the noise determination result, is described in Japanese Patent No. 4053460.
In Japanese Patent No. 4053460, a determination is made based on an image on which expansion processing has been performed. Therefore, it may be impossible to distinguish whether a portion determined to be noise is generated by lossy compression and expansion or is included in the original image before compression and expansion. As a result, for example, even if the degree of compression in the lossy compression method is small and noise is less likely to occur, a portion included in the original image may be falsely determined to be noise and the portion may be eliminated from the image. Furthermore, for example, a similar problem may also occur when data other than image data, such as audio data compressed in the lossy compression method, is expanded.